The invention relates to a method of forming a corner region from a flat sheet, in particular sheet metal plate, and a system for producing a corner region on a component from a flat sheet, bounded on three sides.
By preference, it relates to a corner-forming device adapted by means of an adjusting mechanism to handle a box-type component whereby the adjusting mechanism is used to adjust at least one of either the tool or a roller system to a forward or retracted position in order to adjust the tool exactly to the thickness of the box-type component, thereby obtaining a high degree of accuracy in the dimensions of the corner region of the box-type component.
In housings used to receive electronic instruments, communication devices, circuit boards and similar, the housing is made from a flat piece of plate or a sheet. This type of housing has an opening in the main body and a cover which can be placed on the opening. The cover is designed for opening and closing. The cover is a box-shaped component made from a sheet, which is made by a plate forming process.
If a cover or similar is to be provided on the metal housing, it is made starting from a sheet, which is shaped into a box-shaped component. To this end, rectangular/square cut-outs are made in the four corners of a rectangular standard flat sheet metal plate. The plate is then folded along the four side edges in order to form the four side walls. The corresponding end parts of the oppositely lying side walls are then welded together in order to form a corner region. These corner regions are finished by means of a polishing machine, etc.
Known methods of producing box-shaped components require the following work steps: cutting the parts of material out of the four corners of the plate; folding the plate along the four side edges to form the side walls; welding together the corresponding end parts of adjacent side walls to form a corner region and finishing the corner region with a polishing machine or similar.
These corner regions are therefore formed to produce box-type components by a series of shaping processes of this type. This approach is unacceptable from various points of view because such a large number of work steps complicates the process of making the corner regions of such box-type components and thus increases costs.
Documents DE 40 09 466 C2 and DE 196 14 517 A disclose a corner-forming machine and a method of producing box-type components. With this device, a roll is used as a bending tool for shaping and profiling corners starting from a plate-shaped workpiece, in order to form a planar surface into a corner bounded on three sides. The workpiece is held down on the tool by means of an essentially rectangular-shaped clamp. Fixed in this manner, the plate-shaped workpiece is then shaped using a tool in the form of a roller with an hour glass shape. The clamp and the tool are displaced relative to one another in the plane in which the sheet to be formed is held. This means that the vertical side faces of the plate to be formed project beyond the parallel side faces of the clamp, including when the latter is moved into its sheet-clamping position in readiness for shaping. Using the clamp, coverage of the corner region is provided by the clamp but the material in this region is prevented from being stretched which can lead to tearing in the corner region, which is unacceptable both from an aesthetic point of view and for safety reasons.
Accordingly, DE 196 14 517 A proposed that the oppositely lying vertical side faces of the tool and the clamp should be displaced relative to one another by a horizontal distance and that the face of the clamp should also be inclined. The disadvantage of this approach is that the component is not held firmly between the roll used to shape the component and the clamp and therefore gives in this direction during the rolling process, which leads to warping in the region of the flat sheet-part of the box-type component.
The underlying objective of the present invention is to propose a method of producing corners in box-type components made from flat plates, which enables corner regions for box-type components to be made in a wide variety of external dimensions and thicknesses whilst causing as few problems as possible in terms of finishing, and a system for producing such box-shaped components, by means of which corner regions of different designs can be produced from flat plates at the peripheral region of pre-formed sheet-parts.
This objective is achieved by the invention, independently in each case, by means of the methods described in claims 1 to 4 and 26 and the systems described in claims 28 to 33.
The method described in claim 1 is of advantage because the side walls are guided across the entire height of the tool and lie against its vertical shaping surfaces so that the component can be raised unhindered in a perpendicular direction towards the top face of the tool even if projecting areas have not yet been removed.
The method outlined in claim 2 has the advantage of enabling the projecting region between the side edges of the side walls of the component to be cut off in the corner regions without burring. Due to the fact that the cutting elements can be displaced relative to one another in the same plane as the guide surface, any misalignment in the two side walls forming the corner region can be compensated in the upward direction as the projecting area is cut off, even if tolerances arise as a result of folding when making the side walls.
The advantage of the approach described in claim 3 is that no cambering can occur between the side walls and the flat sheet part of the component as the corner region of the side walls is shaped.
The advantage afforded by the features outlined in claim 4 is that the relative position of the shaping surfaces of the tool can be adjusted and adapted exactly to the cylinder contours of the roller system and its roll, advantageously preventing any indentation or undesirable material deformations in the corner region of the component surface and the shaping region of the roller system or roll because the entire shaping process takes place across the entire forming path.
Claims 5 to 25 describe advantageous features which enable high quality components to be produced.
The process sequence described in claim 26 produces a high surface quality without warping or any undesirable wave-type deformation in the corner region of the material.
The process sequence described in claim 27 ensures that the transition region of the side walls is not misaligned in the corner region.
A system design as described in claim 28 offers an advantage because it prevents the projecting area from being deformed below the bottom face of the tool.
Claim 29 provides an advantageous arrangement in which the cutting elements exactly adjoin the actual contour of the side edges and can be adapted to projections in the transition region without having to be manually re-positioned.
The solution offered in claim 30 advantageously ensures that the plate-shaped sheet part of the component stays flat.
As a result of the arrangement outlined in claim 31, surface roughening due to too high friction forces on the component is significantly reduced or totally avoided whilst the cooling process and lubricating process also enable higher throughput rates.
With the embodiment defined in claim 32, the shape of the cylinder contour or geometry of the roll in the roller system can be accurately adapted to different shapes of corner regions. A roller system incorporating the tools needed to impart the respective shape to the corner region can be held in readiness and it, as well as the tool, can be adapted with little manual handling by adjusting the corner regions.
An arrangement of the type described in claim 33 enables the absolute minimum in tolerance limits to be obtained in the shaping and transition region when forming the corner region, thereby obviating the need for cost-intensive finishing.
Other advantageous embodiments are described in claims 34 to 37, which make for cost-effective and hence economic plant and equipment for producing components.
Claim 38 describes an advantageous embodiment as a result of which a very compact and space-saving unit can be obtained, offering considerable simplifications in the control unit for implementing the shaping process and safety control to protect operating personnel.
Another possible embodiment is described in claim 39, whereby the roll used to shape the corner region can be rapidly changed so that the shaping device can be adapted to suit different shaping specifications, e.g. corner radius, etc..
Finally, the embodiment defined in claim 40 is of advantage since it enables very high clamping forces to be applied and thus produces accurate shaping.